Contributed by by Kudakwashe Chikwava MB ChB. and Csaba Galambos MD.
Published on line in May 2005
The patient, a 14-year-old with hypothyroidism since birth for which he was taking Synthroid (Levothyroxine), developed a nodule in the right lobe of the thyroid. The clinical working diagnosis was autoimmune thyroiditis. The family history was non-contributory. An ultrasound scan showed a hypoechoic nodule, and the thyroid function tests were all within normal limits. A fine needle aspiration was non-diagnostic; hence a right thyroid lobectomy was performed.
The specimen (Fig. 1) consisted of a 6.3 x 3.4 x 2.9 cm lobe of red-tan thyroid weighing 28.0 grams. Sectioning revealed an encapsulated ovoid 2.7 x 2.0 x 2.0 cm tumor mass that expanded the mid-portion of the lobe anteriorly, and was composed of a variegated and mottled red-tan, and focally hemorrhagic granular tissue. The surrounding thyroid parenchyma was compressed and attenuated.
The nodule was composed of a proliferation of follicular epithelial cells with a predominantly solid and micro-follicular growth pattern (Fig. 2). The cells were large showing abundant cytoplasm and mostly round to oval nuclei with no identifiable inclusions or grooves (Fig. 3). Focally, atypical including giant hyperchromatic nuclei and mitoses were seen (Figs. 4 and 5). Hyalinization and central hemorrhage were prominent. The tumor was well encapsulated by a thick fibrous capsule with a focal area of tumor mushrooming, but no extracapsular extension was present (Fig. 5). The background thyroid was multinodular with thick bands of fibrosis separating variably sized areas where the hyperplastic cells showed focal papillary projections and prominent scalloping of the colloid (Fig. 6). No significant lymphocytic infiltrate was identified.